Last week, we talked about how to find the constellation of Cygnus the swan, and the very special object located between the stars Alberio, the eye of the swan, and Deneb, the tail.

Cygnus X-1 was the first candidate they located that fit Stephen Hawking’s theories about the existence of black holes, a theory we now believe to be true.

You’ve probably heard about black holes and seen them included in many a science fiction plot — most series will get there eventually (or more than once). And that’s because they’re still so strange and mysterious to us. But what is a black hole, exactly, at least as far as we know?

Black holes are areas of space that have such strong gravity that not even light is able to escape its grasp. This powerful pull is because black holes have a ton of matter stuffed into a tiny amount of space compared to other objects in our universe. An analogy would be to imagine an object the size of our sun (remember, 1.3 million Earths can fit into the sun at its current size) and to cram it all into the space of your house.

How does something like that happen? Well, it depends on the type of black hole. There are three types of black holes (that we know of): Primordial, stellar and supermassive.

Primordial black holes are the smallest, maybe only the size of a single atom, but with a mass akin to Mt. Shasta. Scientists think these were formed not long after the universe began in the big bang.

The most common type, and the one you see spaceships trying to escape the gravity of all the time, are stellar black holes. These occur as part of the end of the lifecycle of a supermassive star (way bigger than the size of our sun). The core of a giant sun collapses in on itself, causing a supernova, or massive explosion that shoots part of the star into space. The rest of the star is stuffed into the core of the black hole, where it continues to have the same strength of gravity as when it was massive, but whittled down into a much smaller package.

Supermassive black holes are the types of black holes that you’d find at the center of our galaxy. They are, as you might suspect, super massive — their mass is greater than that of a million suns, yet would fit in a sphere the size of our solar system. Scientists think that all large galaxies have a supermassive black hole at their center, and that they formed at the same time as their galaxy.

I know your next question: If light can’t escape from a black hole, how do we know they exist at all?

We can find black holes because of their effect on other nearby bodies. Sometimes, we’ll be able to see an accretion disk as gas is pulled off of a nearby star and swirled around toward the black hole until it ultimately drains into the center. X-ray light is also released by black holes, and we have special telescopes, such as the Chandra X-Ray Observatory, which can measure those emissions.

What would it be like to be sucked into a black hole? Let’s go with not fun.

There’s a great word for what happens to you as you get closer to the event horizon (the point of no return, where the gravity is far too strong to escape) of a black hole: spaghettification. Because you get pulled and stretched to be longer and thinner, just like spaghetti.

Many people might be OK with being a little taller and a little skinnier, but I’d recommend going with a less drastic plan, one you might actually get to come back from.

LOOKING UP THIS WEEK >> At dusk, you’ll see Jupiter high in the southern sky and a very bright Venus in the west with a rising Saturn and later Mars in the southeast. Mars will continue to be bright this month, outshining the neighboring Saturn. You may be able to spot Mercury this week if you’re an early riser. It will rise about an hour and a half before sunrise in the east. The moon is currently a waning gibbous and will be third quarter Sunday.